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Biomedical subjects

N Tonami

Publications and source records attributed to N Tonami.

At least 163 records · Page 9Linked to original sources
PubMed1994

[Quantitative analysis of 123I-BMIPP imaging in relation to exercise-redistribution 201Tl in patients with old myocardial infarction].

Myocardial kinetics of 123I-labeled 15-(p-iodophenyl)3R,S-methylpentadecanoic acid (BMIPP) was evaluated with BMIPP imaging in conjunction with stress-201Tl. We studied 20 patients with old myocardial infarction. BMIPP SPECT was obtained at 20 min and 3 h after injection. On a separate day, exercise stress-201Tl SPECT was performed at 10 min and 3 h after injection. Then, left ventricular myocardium was divided into 20 segments. For quantitative analysis, in each SPECT data, the maximum value (average counts per pixel) of all 20 myocardial segments was taken as 100%; the other values were calculated as a percentage of this maximum (Relative regional uptake, RRU). On the basis of stress-201Tl pattern, the myocardial segments were classified into 4 groups; normal 201Tl uptake, reversible 201Tl defect, fixed 201Tl defect and 201Tl defect with reverse redistribution. The 20 min BMIPP showed reduced activity compared with 3 h-201Tl (p < 0.001), especially in the area of 201Tl redistribution (50/111 segments, 45%), implicating impaired fatty acid utilization at resting condition. The washout rate of the segments with reversible 201Tl defect (-1.6 +/- 13.9%) was significantly lower than that of the segments with normal 201Tl uptake (9.0 +/- 9.8%) and fixed 201Tl defect (3.8 +/- 12.9%). Thus, BMIPP in combination with stress 201Tl imaging provides precise informations of impaired myocardial fatty acid utilization in patients with old myocardial infarction.

Adult↗
PubMed1994

Left ventricular functional reserve in nonobstructive hypertrophic cardiomyopathy: evaluation by continuous left ventricular function monitoring.

UNLABELLED: The cardiac functional response to exercise in patients with nonobstructive hypertrophic cardiomyopathy (HCM) was evaluated using a continuous ventricular function monitor with a cadmium telluride detector (CdTe-VEST). METHODS: Supine ergometric exercise was performed under CdTe-VEST monitoring in 41 patients with nonobstructive HCM (34 men and 7 women, age 18-72 yr, mean 51 yr) and 15 patients without cardiac disease (9 men and 6 women, age 36-56 yr, mean 49 yr). RESULTS: Although 20 of 41 patients with HCM maintained a LVEF above baseline at peak exercise (Group A), 21 did not show an EF increase at peak exercise (Group B). Exercise duration and work load in Group A were longer and higher, respectively, than in Group B. Resting EF in Group B (72 +/- 7.7%) was significantly higher than that in Group A (65 +/- 8.2%) and the control group (62 +/- 5.9%). The EF increase from baseline to EF overshoot during recovery and the time to EF overshoot were lower and longer, respectively, in Group B than in Group A and the control group. Septal wall thickness and the septum-to-posterior-wall-thickness ratio between Groups A and B were not different. ST-segment depression was observed in all 21 Group B patients and in 8 of the Group A patients. CONCLUSION: In patients with nonobstructive HCM, left ventricular dysfunction during exercise and during recovery was frequently observed but was not related to the degree of septal wall hypertrophy. The CdTe-VEST is a useful means to evaluate left ventricular functional reserve to exercise in patients with HCM.

Adolescent↗
PubMed1994

[123I-BMIPP whole-body scintigraphy in relation to left ventricular ejection fraction].

Heart uptake and clearance of 123I-15-(p-iodophenyl)-3(R,S)-methylpentadecanoic acid (BMIPP) by whole-body scintigraphy in relation to left ventricular injection fraction (LVEF) was evaluated in 19 patients with myocardial infarction. At 45 and 210 min after injection, anterior whole-body images were obtained with a single-headed gamma camera system. In each patient, gated blood pool scintigraphy was also performed, and LVEF was calculated. Percent washout from the heart from the 45 to the 210 min imaging positively correlated with LVEF (r = 0.61, p < 0.01), although percent uptake and count density of the heart at 45 min imaging did show any positive correlation with LVEF (r = -0.10 and r = 0.35, respectively). The count density did not correlated with the percent washout (r = 0.32, p = 0.18). Thus, some relationship between LVEF and washout rate of BMIPP from the heart was suggested by analysis of BMIPP whole-body scintigraphy in patients with myocardial infarction.

Adult↗
PubMed1994

[A simple method to obtain semi-quantitative index of brain perfusion using 99mTc-HMPAO].

We developed a new noninvasive index (brain uptake ratio, BUR) inferring brain perfusion using 99mTc-HMPAO scintigraphy, and compared with the index (brain perfusion index, BPI) reported by Matsuda, et al. BUR was obtained for 208 cerebral hemispheres from 104 cases as a ratio of radioactivity in a brain against that passing through an aortic arch. BUR correlated well with BPI (r= 0.965, p < 0.01). Information in deep or occipital regions was reflected well to BUR when data of SPECT images were used. BUR can be obtained even with a small field-of-view gamma camera. BUR is easily obtained and thought to be useful as a semi-quantitative index of brain perfusion.

Adult↗
PubMed1994

[Clinical usefulness of thallium-201 chloride in the diagnosis of tumor (II)--An evaluation in bone, soft tissue and mediastinal tumors].

The clinical usefulness of scintigraphy with thallium-201 (201Tl) chloride injection was evaluated in 79 patients with suspected bone, soft tissue or mediastinal tumors. No abnormal changes of subjective or objective signs and clinical test values were observed post injection. It is considered that 201Tl chloride is a safe radiopharmaceutical. In comparison with benign tumors, malignant tumors showed longer retention or more increased uptake of the 201Tl in the lesions on delayed images. The results suggested that the evaluation of changes of 201Tl uptake might be useful to some extent to differentiate malignant tumor from benign tumor. It is considered that 201Tl scintigraphy is useful for evaluating the location and extent of tumor and differentiating malignant from benign tumor.

Adolescent↗
PubMed1993

[67Ga SPECT in the evaluation of orbital and ocular mass-like lesions].

We evaluated 67Ga SPECT in the differentiation of mass-like lesions in the orbital and ocular areas. A two-headed SPECT system equipped with parallel-hole collimator was used. 67Ga SPECT demonstrated three dimensionally the extent of tumors found by CT and MRI. 67Ga SPECT was especially useful in the assessment of localized lesions in and around the lacrimal gland. In a total of 43 patients studied, the overall accuracy of 67Ga SPECT in diagnosing orbital and ocular lesions was 72%. Sixteen of 21 malignant lesions (76%) showed true positive findings and 15 of 22 benign lesions (68%) showed true negative findings. All seven malignant lymphoma lesions showed true positive findings. One of four cases of malignant melanoma was not visualized. This lesion was less than 15 mm in diameter. None of the three cases of retinoblastoma was visualized, regardless of tumor size. Four of seven cases of pseudotumor or pseudolymphoma showed false positive findings. The differentiation of pseudotumor and pseudolymphoma from malignant lymphoma seemed to be difficult. We conclude that 67Ga SPECT is useful in the differentiation of lesions in the orbital and ocular areas and that evaluation of the extent of malignant lesions can be improved by comparing the findings obtained by morphological diagnostic modalities.

Adult↗
PubMed1993

Regional uptake of iodine-125-metaiodobenzylguanidine in the rat heart.

Regional uptake of iodine-125-metaiodobenzylguanidine ([125I]MIBG) was evaluated in normal (n = 12) and reserpinized (n = 12) rat hearts. At 15 min and 1, 3 and 6 h after injection of [125I]MIBG, tissue activities were calculated for the right ventricular myocardium (RV), the whole left ventricular myocardium (whole LV), the epicardial layer of the left ventricular myocardium (Ep LV), the endocardial layer of the left ventricular myocardium (En LV), the basal segment of the left ventricular myocardium and the apical segment of the left ventricular myocardium. The uptake of [125I]MIBG at 6 h after injection in the normal rat heart was higher in RV than in whole LV (0.45 +/- 0.09% vs 0.30 +/- 0.06% kg dose/g), and in Ep LV than in En LV (0.32 +/- 0.07% vs 0.25 +/- 0.05%). In the reserpinized rat heart, the difference in the uptake between Ep LV and En LV was smaller. This suggests that the difference in the regional [125I]MIBG uptake might reflect different intravesicular uptake in the layers of the heart. To our knowledge, the low uptake in the endocardial layer was a new finding which seems to indicate a difference in innervation between the epicardial and endocardial layers of the left ventricle in the rat heart. Autoradiographic study also showed the low uptake of [125I]MIBG in the endocardial layer, while homogeneous perfusion was observed with thallium-201, supporting the tissue uptake study. Thus, the endocardial and epicardial layers of the left ventricle in the rat heart were considered to be differently innervated.

3-Iodobenzylguanidine↗
PubMed1993

Noninvasive measurements of regional cerebral blood flow using technetium-99m hexamethylpropylene amine oxime.

The previously reported method for quantitative measurements of whole-brain or hemispheric-brain perfusion using technetium-99m hexamethylpropylene amine oxime (HMPAO) radionuclide angiography is now further developed so that regional cerebral blood flow (rCBF) can be measured. Lassen's correction algorithm is used for the linearization of a curve-linear relationship between the radioactivity in the brain and blood flow as seen with single-photon emission tomography (SPET) images. In this algorithm, the cerebral hemisphere was chosen as the reference region and the correction factor alpha was adapted to rCBF in the reference region. This new method of measuring CBF from SPET has been validated in 33 normal subjects and 22 patients with cerebrovascular disease. Regional CBF values in 20 brain regions of the normal subjects were in good agreement with reported values measured by other methods. Regional CBF in the frontal cortex was greater than that in the temporal, parietal or occipital cortex for the entire age range. This hyperfrontal perfusion tended to be less pronounced with advancing age. Seventeen patients with unilateral brain infarction showed significantly lower rCBF than normal subjects. The infarct core showed a low rCBF value of 11.1 ml/100 g/min on average. An increase in rCBF after acetazolamide administration was observed and measured with this method in five patients with unilateral occlusive vascular pathology. These results suggest that this non-invasive method (without any blood sampling) permits the routine measurement of rCBF from HMPAO SPET tomograms of blood flow.

Acetazolamide↗
PubMed1993

Visualization of the thymus with therapeutic doses of radioiodine in patients with thyroid cancer.

Two cases of papillary carcinoma of the thyroid are presented in which whole-body scans following therapeutic doses of iodine-131 revealed intense anterior mediastinal uptake. In both cases, the mediastinal uptake was absent from scans obtained after removal of the entire thymus. Histologically, the resected thymus glands showed hyperplasia and contained neither thyroid tissue nor metastatic foci of thyroid carcinoma. We therefore concluded that anterior mediastinal uptake of radioiodine may be caused by hyperplasia of the thymus.

Adult↗
PubMed1993

Postpartum thyroiditis. A clinical, histologic, and immunopathologic study of 15 cases.

Fifteen specimens from 15 patients with clinically and laboratory-proven postpartum thyroiditis were examined histologically; 8 specimens were obtained during the hypothyroid phase and the other 7 during the recovery euthyroid phase. All specimens showed focal or diffuse chronic thyroiditis. In the eight specimens taken during the hypothyroid phase and four specimens during the early recovery phase, follicular disruption and hyperplastic change of the follicle were common and characteristic histologic features. In the three specimens taken during the late recovery phase, only focal infiltration of lymphocytes was observed. This histologic change resembled that in spontaneous silent thyroiditis, as shown in the authors' previous study. The authors believe that postpartum thyroiditis and spontaneous silent thyroiditis may fit the same category clinically and histologically. In addition to performing the histologic examination, the authors examined the intrathyroidal lymphocyte subsets and HLA-DR antigen expression in the follicular cells immunohistochemically and compared them with those in chronic thyroiditis (usual type). In postpartum thyroiditis, a significant increase of helper-T-cell numbers and increased expression of HLA-DR antigen in the follicular cells were observed, suggesting an enhancement of autoimmune reactivity.

Adult↗
PubMed1993

Renal perfusion with Tc-99m DTPA--simple noninvasive determination of extraction fraction and plasma flow.

A simple, noninvasive method for the determination of extraction fraction and renal plasma flow in Tc-99m DTPA studies is presented. This method could be performed in conjunction with the measurement of glomerular filtration rate, providing additional information about renal plasma flow. Graphic analysis of the Patlak plot was employed for the determination of the unidirectional influx rate constant (ku) of Tc-99m DTPA from the blood to the kidney and the initial nonspecific distribution volume (Vn) in the kidney. The first pass extraction fraction was estimated from Ku and Vn, assuming a bolus input to the kidney. The glomerular filtration rate was measured by renal counting corrected for depth and dose. Using the estimated extraction fraction (EF) and glomerular filtration rate (GFR), the renal plasma flow (RPF) was calculated using the formula of RPF = GFR/EF. In a total of 76 kidneys in 38 patients (including 9 patients with normal renal function and without evidence of nephrourologic disease), the value of renal plasma flow showed good correlation with that of effective renal plasma flow measured by renal counting with I-131 orthoiodohippuran. There was a characteristic tendency for the extraction fraction to show a larger value as the renal plasma flow decreased. These results indicate that this method is valid for renal plasma flow estimation and the determinations of extraction fraction and renal plasma flow in Tc-99m DTPA studies is helpful as an adjunct to the measurement of glomerular filtration rate in order to adequately assess the pathophysiologic changes of renal disorders.

Adult↗
PubMed1993

Intense gallium-67 uptake in ovarian dysgerminoma.

In a patient with an ovarian dysgerminoma, intense uptake of gallium-67 citrate was demonstrated. This report indicates that dysgerminoma should be added to the list showing abnormal accumulation of gallium-67 citrate in the abdomen.

Adolescent↗
PubMed1993

99mTc colloid and 99mTc IDA imagings in diffuse hepatic disease.

Ninety-six patients with various diffuse hepatic diseases were observed using both 99mTc colloid and 99mTc iminodiacetic acid (IDA), focusing on the potential etiologies of the disease process as well as its chronicity and severity. The presence of acute hepatic disease was more sensitively depicted with 99mTc IDA than with 99mTc colloid. In chronic hepatic disease, on the other hand, 99mTc colloid and 99mTc IDA demonstrated a similar sensitivity. The potential etiology of the disease process (differential diagnosis) and the chronicity of the disease could be evaluated better with 99mTc colloid. Among the patients with different stages of liver cirrhosis, however, 99mTc IDA significantly discriminated the severity of the hepatic disease. These results suggest that 99mTc IDA may be used to determine the degree of functional disorder in acute hepatic disease and evaluate the severity of diffuse hepatic disease, whereas 99mTc colloid can effectively evaluate the potential etiology and chronicity of the disease.

Colloids↗
PubMed1993

Evaluation of suspected malignant pulmonary lesions with 201Tl single photon emission computed tomography.

201Tl single photon emission computed tomography (SPECT) was evaluated in 170 patients suspected of having a malignant pulmonary lesion greater than 20 mm in diameter on the surgical specimen. Delayed SPECT (at 3 h after injection) visualized all of the 147 malignant pulmonary lesions and 16 of the 23 (69.6%) benign pulmonary lesions, and generally exhibited the lesion more clearly than the early SPECT images (at 15 min after injection). There was no significant difference in delayed ratio (uptake ratio of the lesion to the normal lung on delayed scan) among the various histological groups except between the adenocarcinoma and large cell carcinoma groups (P < 0.05), and no difference was noted between the malignant and benign lesions. However, in retention index (degree of retention in the lesion) a significant difference was noted between the malignant and benign lesions (P < 0.01), although there was no significant difference in this index among malignant different histology groups. These results indicate that this method is useful for visualizing malignant pulmonary lesions greater than 20 mm in diameter to exclude the possibility of malignancy in the lesions when no abnormal 201Tl accumulation is observed. When the lesion shows abnormal 201Tl accumulation, the retention index seems to help differentiate malignant from benign lesions.

Adenocarcinoma↗
PubMed1993

Iodine-induced hypothyroidism: a clinical and histological study of 28 patients.

Thirty-three thyroid specimens obtained from 28 patients with clinically and laboratory-proven iodine-induced hypothyroidism were examined clinically, histologically, immunohistochemically, and ultrastructurally. Twenty-eight specimens obtained during the hypothyroid phase showed common histological changes in the thyroid thought to be specific for this disease; hyperplastic change in the follicles with some papillary folding, cuboidal to columnar change of follicular cells with clear and vesicular cytoplasm, scanty or absent colloid material in the large distended follicles, and occasional dilatation of capillary vessels. Lymphocytic infiltration was present in about half of the specimens. No specimens showed either stromal fibrosis or parenchymal atrophy. Immunohistochemical and electron microscopic examination revealed that severe interference with thyroid hormone biosynthesis occurs in the follicular cells. In two patients who had a follow-up biopsy in the recovery (euthyroid) phase after iodine restriction, the histological involvement seen in the hypothyroid phase was no longer present. The histological changes in the thyroid gland seen in patients with iodine-induced hypothyroidism are characteristic. This disease can be diagnosed from laboratory tests, but thyroid biopsy is also a useful tool to differentiate this condition from other diseases causing hypothyroidism. Not only clinicians, but also pathologists, must pay attention to this type of hypothyroidism, because thyroid function may revert to normal by iodine restriction alone.

Adult↗
PubMed1993

[Evaluation of early kinetics of 123I-BMIPP in patients with ischemic heart disease].

Early kinetics of 123I-BMIPP was evaluated in 200 left ventricular myocardial segments from 10 patients with old myocardial infarction, employing dynamic SPECT. Dynamic SPECT acquisition was performed from 2 minutes to 14 minutes after injection of 123I-BMIPP. Conventional static SPECT with 123I-BMIPP (BM-S) at 20 min after injection and delayed image from stress 201Tl SPECT (Tl-RD) were visually evaluated by dividing each myocardial segment into the following four groups, NL (the segments with normal radioactivity in BM-S and Tl-RD), Tl < BM (the segments with reduced radioactivity in Tl-RD compared with BM-S), Tl > BM (the segments with reduced radioactivity in BM-S compared with Tl-RD) and Tl = BM < NL (the segments with equally reduced radioactivity in BM-S and Tl-RD). In the dynamic SPECT, washout rate (WR) from 2-4 to 12-14 minutes images was calculated. The WR of Tl > BM group (12.9 +/- 15.5% (mean +/- SD), 55 of 200 segments) was significantly higher than those of NL (-8.6 +/- 11.9%, 95 of 200 segments), Tl = BM < NL (-0.6 +/- 16.0%, 45 of 200 segments) and Tl > BM (-4.4 +/- 9.2%, 5 of 200 segments) groups. This high WR of Tl > BM group may reflect "back diffusion" from myocardium in early phase after injection of 123I-BMIPP.

Adult↗